Vibrational Raman and infrared spectroscopic transitions are used to probe the dynamical and conformational properties associated with lipid-lipid and lipid-protein interactions in membrane bilayer systems. In particular, the concerted interactions of both intrinsic and extrinsic bilayer components upon the three distinct molecular regions of a membrane were examined. Thus, the interrelated perturbations of the head-group, interfacial and acyl chain regions from cholesterol (7-30 mole percent) and water (0.3-4 molecules) were studied both individually and synergistically. In clarifying the dependence of lipid-protein interactions on acyl chain saturation, membrane recombinants of the myelin proteolipid apoprotein with saturated and unsaturated bilayer matrices were examined by Raman spectroscopy. As a consequence of packing arrangements and diffusion properties characteristic of the two classes of lipids, the apoprotein significantly affects the inter- and intramolecular order parameters of saturated lipids, while only slightly affecting those for the unsaturated bilayers.